This invention relates to a transmission-reception circuit including data input/output circuits for full duplex communication, and particularly to a data input/output circuit, which is easy to be incorporated in an LSI which digital apparatus has, or is suited to be constructed in, a CMOS-LSI which includes a data input/output buffer for data input and output and so on.
An example of the full duplex receiving circuit constructed within a CMOS-LSI is described in the Proceedings of ICCD, 1990, pp.430-433, "Simultaneous Bidirectional Signalling for IC Systems" by Kevin Lam, Larry R. Dennison, William J. Dally and others.
In the transmitting circuit according to the above document, the terminal circuit is formed by MOS resistance of the region in which the drain current-voltage characteristic curve rises up from zero because of the necessity for impedance matching between the current drive type transmitting circuit and the transmission path. The receiving circuit has a sense amplifier formed of a CMOS circuit, and constitutes a full duplex transmitting and receiving circuit together with the above transmitting circuit and another transmitting circuit for a reference circuit.
According to the above document, since bidirectional transmission can be made on a single signal line, the number of signal lines can be reduced. However, since the terminal resistance must match the characteristic impedance of the transmission path, the current drive type driver and the parallel terminal MOS resistance are used to constitute the terminal circuit. Therefore, correction circuits are required to correct the terminal resistance and the output current variation of the current drive type driver due to the dispersion in the LSI manufacturing process.